Trials with new acoustic deterrents in the Atlantic pelagic longline fishery

Danielle and Andy are working with fishermen in the North Carolina pelagic longline fishery to trial a new acoustic deterrent, the Dolphin Interactive Dissuasive (DiD) device.  Pilot whales are believed to mainly eat squid, but some short-finned pilot whales interact with pelagic longline fishing gear and remove bait and hooked tuna, a behavior known as depredation.  Depredation results in increased costs and lost revenue for the fishery due to a reduction in the quantity and value of catch and damage to gear.  In addition, pilot whales may become entangled or hooked and die in fishing gear while engaging in depredation.  For these reasons fishermen, scientists and managers are motivated to find ways to deter pilot whales from interacting with longline gear.

Depredated Tuna
Depredated tuna head

DiD devices are intended to produce aversive sounds that interfere with toothed whale echolocation, but only produce sound when they detect cetacean echolocation signals.  Our primary research objectives are to determine whether the devices can be used practically in this fishery, assess the interactive function of the devices, and test their efficacy in reducing depredation.  A fisherman in Wanchese, NC is putting the DiDs on his longline gear and recording data on a number of variables including the amount of fish caught, the amount of fish depredated, and the presence of pilot whales for each longline set.  We will compare data collected from longline sets equipped with DiDs (active) to sets with no DiDs (control) and determine if the acoustic deterrents are successful in decreasing pilot whale interactions in this fishery.  Stay tuned for future results!

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Dolphin Interactive Dissuasive (DiD) device